[Molecular aspects of anthrax pathogenesis]

Zh Mikrobiol Epidemiol Immunobiol. 2014 Jul-Aug:(4):92-101.
[Article in Russian]

Abstract

A model of anthrax infection with the role determined for main pathogenicity factors of Bacillus anthracis exotoxin and capsule is presented. After spore phagocytosis by macrophages, synthesis of the main exotoxin component begins - a protective antigen that in oligomeric form disrupts phagosome membrane. This accelerates the transition of the pathogen from phagosome into the macrophage cytoplasm. Poly-D-glutamine capsule synthesized by the pathogen triggers the exit (exocytosis) of vegetative cells from macrophages and protects them from re-phagocytosis in lymphatic node lumen. The vegetative cells, that actively and freely replicate in lymphatic node, secret an exotoxin that disrupts endothelial septum between lymph and blood due to cytotoxic activity. As a result the vegetative cells get into blood and bacteremia develops. Pathogenetic pattern during anthrax (multiple hemorrhages in various organs etc.) is associated with local microcirculation disorders of various organs caused by the effect of bacterial exoproteases via activation of Willebrand factor. This results in a rapid local increase of microbial mass and consequent powerful cytotoxic effect of exotoxin on the tissue cells of the affected organ. Death of the infected organism takes place at the final stage of infec- tion due to toxic shock caused by the exotoxin. A reduction of body temperature takes place after death and the process of spore formation begins in the dead animal: capsule depolymerization, chain shortening, peptidoglycan cortex formation. Spores in this form are the prolonged source of infectious agent conservation and spread of infection in nature.

Publication types

  • English Abstract
  • Review

MeSH terms

  • Animals
  • Anthrax / microbiology*
  • Anthrax / pathology
  • Bacillus anthracis / genetics
  • Bacillus anthracis / pathogenicity*
  • Exotoxins / genetics
  • Exotoxins / metabolism*
  • Macrophages
  • Phagocytosis / genetics
  • Phagosomes / metabolism
  • Spores, Bacterial / genetics
  • Spores, Bacterial / pathogenicity
  • Virulence / genetics

Substances

  • Exotoxins